$\sqrt{\frac{4}{3}} - \sqrt{\frac{3}{4}} = x$
Aptitude
Square Root and Cube Root
Difficulty: Easy
Choose an option
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A$\frac{4\sqrt{3}}{6}$
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B$\frac{1}{2\sqrt{3}}$
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C1
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D$-\frac{1}{2\sqrt{3}}$
Answer
Correct Answer: $\frac{1}{2\sqrt{3}}$
Explanation
Concept & Math
When subtracting fractional radicals, extract the roots of the numerator and denominator separately where possible. Then, rationalize the denominators or find a common denominator to combine the terms.
Step-by-Step Solution
* Given expression: $\sqrt{\frac{4}{3}} - \sqrt{\frac{3}{4}} = x$
* Apply the square root separately to the numerators and denominators:
$\frac{\sqrt{4}}{\sqrt{3}} - \frac{\sqrt{3}}{\sqrt{4}}$
* Evaluate the perfect squares ($\sqrt{4} = 2$):
$\frac{2}{\sqrt{3}} - \frac{\sqrt{3}}{2}$
* Find a common denominator to subtract the fractions. The common denominator is $2\sqrt{3}$.
* Multiply the first term by $\frac{2}{2}$ and the second term by $\frac{\sqrt{3}}{\sqrt{3}}$:
$\frac{2 \times 2}{2\sqrt{3}} - \frac{\sqrt{3} \times \sqrt{3}}{2\sqrt{3}}$
* Simplify the numerators:
$\frac{4}{2\sqrt{3}} - \frac{3}{2\sqrt{3}}$
* Combine the fractions:
$\frac{4 - 3}{2\sqrt{3}} = \frac{1}{2\sqrt{3}}$
* Thus, $x = \frac{1}{2\sqrt{3}}$.
Exam Strategy & Shortcut
You can treat $\sqrt{\frac{4}{3}}$ and $\sqrt{\frac{3}{4}}$ as variables $a$ and $\frac{1}{a}$ where $a = \frac{2}{\sqrt{3}}$. The expression is $a - \frac{1}{a}$. So, $\frac{2}{\sqrt{3}} - \frac{\sqrt{3}}{2}$. Cross-multiplying gives $\frac{4 - 3}{2\sqrt{3}} = \frac{1}{2\sqrt{3}}$. This visual shortcut skips redundant radical writing steps.
Common Pitfall
A common error is attempting to combine the terms under a single root by subtraction, incorrectly assuming $\sqrt{a} - \sqrt{b} = \sqrt{a - b}$. This leads to fundamentally flawed logic and wrong answers. Radicals must be evaluated or combined using common denominators.
Final Answer
Therefore, the correct answer is **$\frac{1}{2\sqrt{3}}$**.